The man is Professor Carl Wunsch, Cecil and Ida Green Professor of Physical Oceanography at MIT, and it's worth pondering his words carefully, not least because he is angry about the way he was persuaded to participate in the filming of the Channel 4 documentary The Great Global Warming Swindle.

Wunsch isn't a sceptic. He wrote:

I believe that climate change is real, a major threat, and almost surely has a major human-induced component.

But he also wrote:

I am on record in a number of places complaining about the over-dramatization and unwarranted extrapolation of scientific facts. Thus the notion that the Gulf Stream would or could "shut off" or that with global warming Britain would go into a "new ice age" are either scientifically impossible or so unlikely as to threaten our credibility as a scientific discipline if we proclaim their reality.

Recently, I had a short debate with the pseudonymous blogger Unity, of the Ministry of Truth. It was shorter than I had intended, because of the, um... interesting comments policy at that blog. The first couple of times I commented, my remarks appeared. Then, as I tried to respond to the replies I had first a comment moderation message, then another one, then the message that my comments were filtered out as spam. None subsequently appeared, not the moderated two and not the spam one that was, according to the message, going to be drawn to the site owner's attention.

I'd point Unity to Wunsch's paper, but I doubt the comment would appear. I guess that's one way to win an argument. Or. at least, appear to.

Unity has a specialisation: s/he operates a smoke machine. Vast quantities of words pour out, completely missing the point. The point in this case - and I need to point this out here for reasons that are obvious from the above - is not that systems can be chaotic. Of course they can. It's that this system, the Gulf Stream, isn't likely to tip.

UPDATE: In the comments, Unity insists s/he did approve my comments shortly after I made them. I didn't see them when I checked before writing this post, but Unity seems very honest from what I've seen so I'll accept that, and withdraw my accusation.

Very well, Unity. If you're insistent I'll accept your word and assume I somehow overlooked the appearance of my comments when I checked. From what I've seen of your work that seems the most appropriate response.